Efforts are being made in the motor vehicle industry, in particular in connection with passenger cars, to reduce fuel consumption and pollution. One approach to this objective is to reduce the weight of vehicles.
Parallel with this, there is an ongoing effort to make vehicles safer, which often results in a weight increase because of additional components, for example the installation of transverse rails in the doors and struts in the vehicle cage. The resulting additional weight cannot even remotely be compensated by savings in the interior fittings.
Because of the trend toward smaller engines with improved efficiency, it becomes increasingly necessary to install auxiliary heaters, especially in vehicles of smaller size and medium size, because smaller engines and improved engine efficiency can result in insufficient waste heat for satisfactorily heating vehicle passenger compartments in cold weather.
In a further, parallel occurring development, it is becoming increasingly common to equip even smaller and medium sized vehicles with air conditioners as standard equipment.
Because of the increased employment of auxiliary heaters and air conditioners, gains that have resulted in reductions in fuel consumption and emissions, have been lost, or at least reduced.
On the average, air conditioners weigh 15 to 16 kg, i.e. by far more than can ever be saved in components of the interior fittings. Added to this is that operation of an air conditioner causes an average fuel increase of 0.6 l per 100 km. If an air conditioner is installed, both the weight savings at other places and the reduced consumption achieved thereby are completely or mostly lost. Driving comfort is increased, but consumption and environmental stress are increased.
Auxiliary fuel heaters weigh 2 to 4 kg on the average and consume 0.2 to 0.4 l of fuel per hour. Passive auxiliary heaters, which recover heat from the waste air of the passenger compartment by means of a heat pump, desorption heaters, and the like are limited in their output, most are heavier than auxiliary fuel heaters and because of the use of electric energy are neither more efficient nor, in particular, more ecologically beneficial.
Thus, parallel developments in the manufacture of passenger cars, each of which, when examined by itself, can be considered to be an improvement, as a whole can cancel each other partially out in regard to their ecological consequences.
From the viewpoint of ecology, the strong trend toward air conditioners in particular is a serious backward step. It leads to a considerable increase in fuel consumption and therefore to increased emissions of pollutants. This becomes clear, inter alia, from the recent demands, even from the automobile club sector, to require that manufacturers of vehicles openly disclose, among other technical vehicle data, the increase in fuel consumption as a result of the use of air conditioners, so that the buyer can clearly see what additional operating costs he or she will face in connection with air conditioners, and most of all what he or she has to pay for the luxury of an air conditioner that imposes additional stresses on the environment.
U.S. Pat. No. 2,768,672 discloses a vehicle having partial thermal insulation, which consists of the attachment or connection of asbestos mats to surfaces of the interior bordering the exterior, and which is limited to this. The intended thermal insulation in this known solution has disadvantages, for example higher weight because of the asbestos mats, which neutralize at least a portion of the advantages of thermal insulation.
Thus, in the prior art, motor vehicles for carrying passengers are heat-insulated only in some regions, if at all. Systematic, complete heat insulation is known only in refrigerator vehicles in which heat-sensitive goods are transported.
As an alternative or supplement to air conditioning systems, there are known systems, for instance made by Audi, that remove heat that has already penetrated into the passenger compartment while the vehicle was parked, again using the vehicle blower. Solar cells integrated into the sunroof, for example, furnish the energy required to do so.
Instead of comprehensive heat insulation and flushing out of the heat that penetrates the outer skin, air conditioners, which provide cooled air that absorbs the heat after it has entered the passenger compartment, are being built into vehicles. Air conditioners present the drawbacks already noted above.
Parent U.S. Pat. No. 6,561,562 discloses the concept of insulating passenger-carrying vehicles as extensively as possible, in order to make air conditioners unnecessary, or at least to make it possible to use air conditioners of smaller capacity and thus, with fewer drawbacks. According to that patent, all of the parts of a vehicle forming its boundary with the outside, or at least those parts enclosing the passenger compartment, can be provided with insulating materials or molded insulating parts, in order to prevent the entry of heat into the vehicle interior in the summer and to prevent the loss of heat in winter. That patent also discloses the possibility of providing the roof of an automotive vehicle with a ventilation gap or ventilation channels that allow an air flow for conducting heat convectively to the exterior.